Injection molding is a typical method of molding thermoplastics. In injection molding, products are made by injecting molten plastic into a mold. Therefore, a nozzle for injecting molten plastic into a mold is mounted in an injector.
An injecting nozzle pressure feeds and supplies molten plastic to an injecting mold by using a screw cylinder. Such an injecting nozzle is disclosed in Korean Patent Publication number 100631267 which corresponds to application number 1020050046693 (hereinafter called “prior patent”).
According to the prior patent, an injecting nozzle, as shown in FIG. 1, includes a body 10, a head 20, a poppet 30, and a vent ring 40.
One end of the body 10 is connected to a cylinder (not shown) of an injector, and molten plastic is supplied from the cylinder to the body 10. The other end of the body 10 is coupled with the head 20.
A molten plastic pathway 12 is formed in the body 10, and the poppet 30 and the vent ring 40 are mounted in the molten plastic pathway 12.
The vent ring 40 is inserted in the poppet 30, and a plurality of protrusions 42 are radially protruded at one side of the vent ring 40. Therefore, when the molten plastic passes through an exterior circumference of the poppet 30, gas in the molten plastic is extracted to a space between the vent rings 40.
In addition, a gas exhaust hole 14 is formed from an interior circumference of the body 10 to an exterior circumference of the body 10, and the extracted gas is exhausted to the exterior of the body 10 through the gas exhaust hole 14.
An injecting hole 22 is formed at one end of the head 20. The molten plastic supplied through the molten plastic pathway 12 passes around the exterior circumference of the poppet 30 and is supplied to a mold (not shown) through the injecting hole 22 of the head 20.
However, the gas in the molten plastic is exhausted when the molten plastic passes around the exterior circumference of the poppet 30, but techniques for effectively extracting the gas from the molten plastic are not disclosed according to the prior utility. Therefore, a large amount of gas is contained in the molten plastic injected through the injecting hole 22, and inferior products are produced due to the gas.
In addition, since the vent ring 40 does not effectively extract the gas from the molten plastic, an additional drier may be needed in order to dry the gas in the molten plastic. Therefore, equipment may be complex and product cost may be high.